Bending machines are known, for bending metal products, for example bars, reinforcement round pieces, section bars, pipes or other profiles with any section shape, for shaping stirrups or other shaped elements.
These machines normally consist of a main drawing unit, for example with rolls, which feeds the metal products toward a bending unit, and a shearing unit or shears, interposed between the main drawing unit and the bending unit, which shears the metal products to take them to the size corresponding to the linear development of the segments to be formed.
Since this linear development, or length of the initial metal product when working from segments of a predetermined length, often does not exactly correspond to the length of the sheared metal product or an exact sub-multiple thereof, a terminal segment or offcut remains between the main drawing unit and the shears, which must be removed before a new working cycle is started.
The shaped element still in the machine is no longer gripped in the main drawing unit and therefore it is no longer possible to control its movement, for example to restart the bending by making the metal product move back toward the drawing unit.
Furthermore, when they do not fall by themselves, the offcuts have to be discharged from the axis of feed of the metal product: this must be done manually or using suitable expulsion devices.
The manual solution often entails the need to stop the machine, to remove possible protections and to extract the segment, with obvious downtimes and problems in terms of safety for the operator.
There are also automated expulsion devices which intervene after the shearing so that the offcut is discharged, thus freeing the working axis of the shears and the main drawing unit. However these run the risk that the discharged offcut can interfere with the bending unit or other operating units that may be present on the bending machine, compromising its correct functioning and obliging the operator to intervene in any case.
Furthermore, this solution does not guarantee sufficient safety for the operator, because the offcuts are discharged in an uncontrolled way and can hit the operator.
Moreover, since the shearing unit is interposed between the drawing unit and the bending unit, once the bending operations have been carried out on the metal product being worked, the latter must be moved by the drawing unit in an inverse direction to the normal feed of the metal product, to dispose the segment to be sheared in correspondence with the shearing unit.
The movement of the metal product in the inverse direction entails an increase in the bending times, and in the case of terminal segments of the metal product, it is not always possible to command the movement thereof for the above reasons.
Another disadvantage is the quantity and length of the offcuts. In other words, discarding material to be removed from the work cycle also represents a considerable cost.
These disadvantages can lead to losses in productivity, even considerable ones, for example if the segment jams, or can lead to injury for the operator, for example where the segment goes to an anomalous and unsafe position.
One purpose of the present invention is to obtain a bending machine and a corresponding bending method able to limit the quantity and length of the offcuts to be discharged.
Another purpose of the present invention is to reduce the constructional and management complexity of the machine, reducing the moving parts thereof.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.